Impact of Vaccination on the COVID-19 Pandemic: Evidence from U.S. States

45 Pages Posted: 17 May 2021

See all articles by Xiao Chen

Xiao Chen

Tsinghua University - School of Economics & Management

Hanwei Huang

City University of Hong Kong; London School of Economics & Political Science (LSE) - Centre for Economic Performance (CEP)

Jiandong Ju

Tsinghua University - PBC School of Finance

Ruoyan Sun

University of Alabama at Birmingham - Health Care Organization and Policy

Jialiang Zhang

Peking University - National School of Development

Date Written: May 8, 2021

Abstract

Governments worldwide are implementing mass vaccination programs in an effort to end the novel coronavirus (COVID-19) pandemic. Although the approved vaccines exhibited high efficacies in randomized controlled trials, their population effectiveness in the real world remains less clear, thus casting uncertainty over the prospects for herd immunity. In this study, we evaluated the effectiveness of the COVID-19 vaccination program and predicted the path to herd immunity in the U.S. Using data from 12 October 2020 to 7 March 2021, we estimated that vaccination reduced the total number of new cases by 4.4 million (from 33.0 to 28.6 million), prevented approximately 0.12 million hospitalizations (from 0.89 to 0.78 million), and decreased the population infection rate by 1.34 percentage points (from 10.10% to 8.76%). We then built a Susceptible-Infected-Recovered (SIR) model with vaccination to predict herd immunity. Our model predicts that if the average vaccination pace between January and early March 2021 (2.08 doses per 100 people per week) is maintained, the U.S. can achieve herd immunity by the last week of July 2021, with a cumulative vaccination coverage of 60.2%. Herd immunity could be achieved earlier with a faster vaccination pace, lower vaccine hesitancy, or higher vaccine effectiveness. These findings improve our understanding of the impact of COVID-19 vaccines and can inform future public health policies regarding vaccination, especially in countries with ongoing vaccination programs.

Note: Funding Statement: H.H. is supported by the startup grant from the City University of Hong Kong (grant no. 7200689).

Declaration of Interests: The authors declare no conflicts of interest

Keywords: COVID-19 pandemic, vaccination, herd immunity, SIR

JEL Classification: I10, I18

Suggested Citation

Chen, Xiao and Huang, Hanwei and Ju, Jiandong and Sun, Ruoyan and Zhang, Jialiang, Impact of Vaccination on the COVID-19 Pandemic: Evidence from U.S. States (May 8, 2021). Available at SSRN: https://ssrn.com/abstract=3845163 or http://dx.doi.org/10.2139/ssrn.3845163

Xiao Chen

Tsinghua University - School of Economics & Management ( email )

Hiadian District
Beijing 100084
China
+8610-6278-9863 (Phone)
+8610-6278-5876 (Fax)

Hanwei Huang (Contact Author)

City University of Hong Kong ( email )

10-282 Lau Ming Wai Building
City University of Hong Kong
Hong Kong
Hong Kong

HOME PAGE: http://https://sites.google.com/site/chinahanweihuang/

London School of Economics & Political Science (LSE) - Centre for Economic Performance (CEP) ( email )

Houghton Street
London WC2A 2AE
United Kingdom

Jiandong Ju

Tsinghua University - PBC School of Finance ( email )

No. 43, Chengdu Road
Haidian District
Beijing 100083
China

Ruoyan Sun

University of Alabama at Birmingham - Health Care Organization and Policy ( email )

United States

Jialiang Zhang

Peking University - National School of Development ( email )

No. 5 Yiheyuan Road
Haidian District
Beijing, Beijing 100871
China

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